Was in the electric panel under the driver window with the bus running and touched a wire to the REI radio system amp to supply a voltage to see if it still worked and spark-poof-silence! The bus shut off and now the whole thing is dead as a door nail. I had no idea a single small spark could wipe out the whole bus! Don't even know where to start.

Having recovered from the initial shock and probed a bit further it seems everything works that would work without the ignition switch being on but everything that relies on the ignition is dead. Ideas?

You should have 12 volt feed going from switch back to ddec. on my 89 prevost there was a inline fuse in the front elect compartment after the ign switch. Some have a 12 volt selonoid (sp) activated by ign switch. Get your volt meter out. Some had a inline fuse rite at battery tap (12 volt) all possibilities. I don't have a manual for your coach. Hopefully a MCI guy will chime in. My last MCI was mechanical. Bob

Update! The Po connected the radio cutoff switch to the master control breaker. We fried the breaker when we shorted the radio controller. Moved the master control wiring to an empty breaker and she started right up.